feat(extract): emit WOM and WOB side-files (M2/WMO → open formats)

Extends asset_extract with two more open-format emitters:
  --emit-wom  foo.m2 (+ foo00.skin) → foo.wom
  --emit-wob  foo.wmo (+ foo_NNN.wmo groups) → foo.wob
  --emit-open now also turns these on

Originals are preserved so private servers still load .m2/.wmo
through the manifest path; the wowee runtime/editor pick up the
.wom/.wob next to them via the existing open-format search rules.

Implementation:
- New WoweeModelLoader::fromM2Bytes(m2Data, skinData) shares the
  conversion body with fromM2(path, am) via a static helper
  (convertM2ToWom). Lets the extractor convert without standing
  up an AssetManager.
- fromM2(path, am) moved to a separate translation unit
  (wowee_model_fromm2.cpp) so asset_extract doesn't have to
  link the AssetManager dependency.
- WoweeBuildingLoader::fromWMO already takes a WMOModel directly,
  so emitWobFromWmo just needs to read root + group files and
  call save().
- Group sub-files (<base>_NNN.wmo) are skipped during the walk
  since they're merged into the root WMO.

src/pipeline/wowee_model.cpp

@@ -438,30 +438,28 @@ bool WoweeModelLoader::save(const WoweeModel& model, const std::string& basePath
     return true;
 }
 
-WoweeModel WoweeModelLoader::fromM2(const std::string& m2Path, AssetManager* am) {
+// Internal helper: convert a parsed M2Model (already merged with skin if
+// applicable) into a WoweeModel. Shared by fromM2 (AssetManager path)
+// and fromM2Bytes (extractor path).
+static WoweeModel convertM2ToWom(const M2Model& m2);
+
+// fromM2(path, am) lives in wowee_model_fromm2.cpp so the asset extractor
+// can link wowee_model.cpp without pulling in the AssetManager dependency.
+// convertM2ToWom() (defined below) is the shared conversion body.
+WoweeModel convertM2ToWomShared(const M2Model& m2) { return convertM2ToWom(m2); }
+
+WoweeModel WoweeModelLoader::fromM2Bytes(const std::vector<uint8_t>& m2Data,
+                                          const std::vector<uint8_t>& skinData) {
     WoweeModel model;
-    if (!am) return model;
-
-    auto data = am->readFile(m2Path);
-    if (data.empty()) return model;
-
-    auto m2 = M2Loader::load(data);
-
-    // WotLK+ M2s store header in .m2 but geometry in .skin — always merge the
-    // skin file when present so we get vertices/indices/batches even for M2s
-    // that already report isValid() (older expansions).
-    {
-        std::string skinPath = m2Path;
-        auto dotPos = skinPath.rfind('.');
-        if (dotPos != std::string::npos)
-            skinPath = skinPath.substr(0, dotPos) + "00.skin";
-        auto skinData = am->readFile(skinPath);
-        if (!skinData.empty())
-            M2Loader::loadSkin(skinData, m2);
-    }
-
+    if (m2Data.empty()) return model;
+    auto m2 = M2Loader::load(m2Data);
+    if (!skinData.empty()) M2Loader::loadSkin(skinData, m2);
     if (!m2.isValid()) return model;
+    return convertM2ToWom(m2);
+}
 
+static WoweeModel convertM2ToWom(const M2Model& m2) {
+    WoweeModel model;
     model.name = m2.name;
     model.boundRadius = m2.boundRadius;
 

src/pipeline/wowee_model_fromm2.cpp

@@ -0,0 +1,42 @@
+// AssetManager-bound implementation of WoweeModelLoader::fromM2(path, am).
+// Split out from wowee_model.cpp so the asset extractor can link the core
+// model loader/saver without dragging the AssetManager dependency in.
+
+#include "pipeline/wowee_model.hpp"
+#include "pipeline/asset_manager.hpp"
+#include "pipeline/m2_loader.hpp"
+
+namespace wowee {
+namespace pipeline {
+
+// Friend bridge to the conversion helper defined in wowee_model.cpp.
+WoweeModel convertM2ToWomShared(const M2Model& m2);
+
+WoweeModel WoweeModelLoader::fromM2(const std::string& m2Path, AssetManager* am) {
+    WoweeModel model;
+    if (!am) return model;
+
+    auto data = am->readFile(m2Path);
+    if (data.empty()) return model;
+
+    auto m2 = M2Loader::load(data);
+
+    // WotLK+ M2s store header in .m2 but geometry in .skin — always merge
+    // the skin file when present so we get vertices/indices/batches even
+    // for M2s that already report isValid() (older expansions).
+    {
+        std::string skinPath = m2Path;
+        auto dotPos = skinPath.rfind('.');
+        if (dotPos != std::string::npos)
+            skinPath = skinPath.substr(0, dotPos) + "00.skin";
+        auto skinData = am->readFile(skinPath);
+        if (!skinData.empty())
+            M2Loader::loadSkin(skinData, m2);
+    }
+
+    if (!m2.isValid()) return model;
+    return convertM2ToWomShared(m2);
+}
+
+} // namespace pipeline
+} // namespace wowee